I just bought a very low hours Johnson 25, pull start, tiller. It starts and runs without any problems. However, at certain throttle openings/RPMs it makes a piercing, continuous "ringing" sound that is different from the induction roar. Speed up a little from that throttle setting, it disappears; slow down a little, it disappears. It happens at about three points as RPM increases.
It's loudest at full spark advance, just as the throttle roller lifts off the cam, but it also happens at lower RPM as I mentioned.
Is this characteristic of this motor? I had a 1977 35 hp with the same block, that did not make that sound.
It's a puzzle. Any ideas?
Many thanks!
auldscott
It's loudest at full spark advance, just as the throttle roller lifts off the cam, but it also happens at lower RPM as I mentioned.
Is this characteristic of this motor? I had a 1977 35 hp with the same block, that did not make that sound.
It's a puzzle. Any ideas?
Many thanks!
auldscott